The Hierarchy of Control: 5 Steps for Accident Prevention

Every workplace has hazards, but not all safety measures are equally effective. When an accident happens, it’s often because the right controls weren’t in place, or the ones that were there relied too much on human behavior. The Hierarchy of Control is a proven framework that helps organizations prioritize safety measures from most to least effective. Understanding this five-step approach can mean the difference between preventing an accident and merely reacting to one.

What is the hierarchy of control? 🔗

The hierarchy of controls identifies a preferred order of actions to best manage hazardous workplace exposures. Developed by the National Institute for Occupational Safety and Health (NIOSH), this framework ranks control measures based on their reliability and effectiveness. The system moves from the most effective solutions at the top-those that physically remove hazards-down to the least effective at the bottom, which depend heavily on human behavior.

The hierarchy is typically shown as an inverted pyramid with five levels: elimination, substitution, engineering controls, administrative controls, and personal protective equipment. Controls higher in the hierarchy are more effective because they reduce or remove hazards without requiring constant human interaction, while lower-level controls demand ongoing attention and compliance.

Step 1: Elimination – removing the hazard completely 🔗

Elimination sits at the top of the hierarchy because it is the most effective way to prevent accidents. This method involves completely removing the hazard from the workplace, which reduces the associated risk to zero and eliminates the need for any other controls. When a hazard is eliminated, no exposure can occur, making it the preferred solution.

Examples of elimination include redesigning a work process to avoid using toxic chemicals altogether, removing heavy manual lifting by changing how materials are stored and transported, or eliminating fall hazards by conducting work at ground level instead of at height. According to NIOSH, elimination is easiest to implement during the design or development stage of a project, allowing planners to make significant changes without the need for costly retrofitting later.

Why elimination isn’t always possible 🔗

While elimination is ideal, it’s often the most difficult control to implement in existing operations. Many industrial processes inherently involve hazardous materials or conditions that cannot simply be removed. For instance, construction work will always involve working at heights, and chemical manufacturing requires handling reactive substances. When elimination isn’t feasible, the next best option is to move down the hierarchy to substitution.

Step 2: Substitution – using safer alternatives 🔗

When a hazard cannot be eliminated, substitution offers the next best protection. This involves replacing hazardous materials, processes, or equipment with less dangerous alternatives. Effective substitutes reduce the potential for harmful effects and do not create new risks in the process.

Common examples include replacing solvent-based paints with water-based alternatives, using plastic containers instead of glass to reduce breakage hazards, or substituting loud machinery with quieter models. In manufacturing, automatic handling equipment can replace manual processes that involve repetitive strain or heavy lifting. The key is to carefully evaluate whether the substitute actually reduces risk without introducing new hazards.

Evaluating substitution options 🔗

Before implementing a substitution, organizations must compare the new risks against the original ones. This includes considering how the substitute will interact with other materials and processes in the workplace. For example, switching to a less toxic cleaning chemical is beneficial only if it still effectively performs its intended function and doesn’t react dangerously with other substances present.

Step 3: Engineering controls – physical barriers and modifications 🔗

Engineering controls are the third level of the hierarchy and work by physically separating workers from hazards or removing contaminants from the work environment. These controls are built into the workspace and don’t rely on worker behavior to be effective, making them more reliable than administrative controls or PPE.

Types of engineering controls 🔗

Ventilation systems: Local exhaust ventilation captures contaminants at their source, such as welding fumes or chemical vapors, before they can spread into the worker’s breathing zone. General ventilation systems circulate and replace air throughout a facility to dilute airborne hazards.

Machine guards: Physical barriers prevent body parts from contacting moving machinery parts like saws, presses, or conveyors. Safety interlocks automatically shut down equipment when guards are removed or doors are opened, preventing operation during unsafe conditions.

Noise control: Sound-dampening materials, acoustic enclosures, and vibration isolation reduce worker exposure to hazardous noise levels. Rather than relying solely on hearing protection, these controls reduce noise at the source.

Ergonomic design: Workstations designed to minimize awkward postures, repetitive motions, and excessive force reduce musculoskeletal disorders. This includes adjustable equipment, lift assists, and properly positioned tools and materials.

While engineering controls typically have higher upfront costs than other methods, their long-term operating costs are often lower, especially when protecting multiple workers. They also tend to improve productivity rather than hinder it, unlike some lower-level controls.

Step 4: Administrative controls – changing how work is done 🔗

Administrative controls reduce risk through organizational measures rather than physical changes to the workplace. These controls establish work practices that reduce the duration, frequency, or intensity of exposure to hazards. Because the hazard itself remains present, administrative controls are considered less effective than higher-level controls and depend on consistent human compliance.

Common administrative control measures 🔗

Training and competency: Workers must be trained to identify hazards, understand safe procedures, and know how to protect themselves and coworkers. Training is a key mechanism to ensure workers have learned about workplace hazards and how to limit personal exposure.

Job rotation: Rotating workers through different tasks limits the time any single person is exposed to a particular hazard. This is especially useful for reducing repetitive strain injuries or limiting exposure to noise, heat, or hazardous chemicals.

Safe work procedures: Written procedures outline the safest way to perform tasks or work with hazardous materials. These standard operating procedures provide consistency and reduce the risk of errors that could lead to accidents.

Scheduling controls: Adjusting work schedules to minimize exposure is another administrative approach. This might include conducting maintenance during off-hours when fewer workers are present, or limiting the duration of tasks in hazardous environments.

Warning signs and labels: Visual cues remind workers of hazards and reinforce safety protocols. These include signs for high-voltage areas, chemical warnings, and reminders about required protective equipment.

Limitations of administrative controls 🔗

The main weakness of administrative controls is their reliance on human behavior. Workers may forget procedures, ignore warnings, or become complacent over time. Additionally, these controls require ongoing supervision, regular training updates, and consistent enforcement to remain effective. Unlike engineering controls that work automatically, administrative measures fail when people don’t follow them.

Step 5: Personal protective equipment – the last line of defense 🔗

Personal Protective Equipment (PPE) sits at the bottom of the hierarchy and should be used only when higher-level controls are not feasible or do not provide complete protection. PPE is equipment worn to minimize exposure to hazards, including gloves, respirators, safety glasses, hard hats, hearing protection, and protective clothing.

PPE is considered the least effective control because it does nothing to eliminate or reduce the hazard itself. It only creates a barrier between the worker and the hazard, and its effectiveness depends entirely on proper selection, fit, use, and maintenance. If a respirator is worn incorrectly or safety glasses are not impact-rated for the task, the protection fails.

When PPE is necessary 🔗

Organizations should rely on PPE in three situations: while other controls are under development, when other controls cannot sufficiently reduce hazardous exposure, or when PPE is the only control option available. Employers should not rely on PPE alone when other effective control options are available.

Effective PPE programs include workplace hazard assessments, proper selection and fit testing, regular inspection and replacement of damaged equipment, comprehensive employee training, and ongoing monitoring for continued effectiveness. While PPE may seem less expensive initially, it can be costly over time, especially when multiple workers require daily use.

Combining controls for maximum protection 🔗

A combination of controls is often most effective in managing workplace hazards. Rarely does a single control method provide complete protection. For example, a welding operation might use local exhaust ventilation (engineering control), limit welding time through job rotation (administrative control), and require respirators for breakthrough exposures (PPE).

The key principle is to implement controls as high in the hierarchy as possible, then add lower-level controls as needed for additional protection. This layered approach, often called defense in depth, ensures that if one control fails, others are still in place to protect workers. Organizations should regularly evaluate whether existing controls remain effective and whether technological advances offer better protection options.

What do you think? Looking at your own workplace or areas you’re familiar with, which level of control do you see used most often? Are there hazards that could be better managed by moving up the hierarchy rather than relying on administrative controls or PPE alone?

References

1. https://www.cdc.gov/niosh/hierarchy-of-controls/about/index.html
2. https://www.osha.gov/safety-management/hazard-prevention
3. https://www.actenviro.com/engineering-controls/
4. https://examples-of.net/examples-of-engineering-controls/
5. https://www.ualberta.ca/en/human-resources-health-safety-environment/environment-and-safety/hazard-management/hazard-controls/administrative-controls/index.html
6. https://www.creativesafetysupply.com/glossary/administrative-controls/
7. https://www.osha.gov/sites/default/files/Hierarchy_of_Controls_02.01.23_form_508_2.pdf